HBx drives alpha fetoprotein expression to promote initiation of liver cancer stem cells through activating PI3K/AKT signal pathway

Hepatitis B virus (HBV)‐X protein (HBx) plays critical role in inducing the malignant transformation of liver cells. Alpha fetoprotein (AFP) expression is closely related to hepatocarcinogenesis. We report that Oct4, Klf4, Sox2 and c‐myc expression positively associated with AFP(+)/HBV(+) hepatocellular carcinoma(HCC) tissues, and the expression of the stemness markers CD44, CD133 and EpCAM was significantly higher in AFP(+)/HBV(+) HCC tissues compared to normal liver tissues or AFP (−)/HBV(−) HCC tissues. AFP expression turned on prior to expression of Oct4, Klf4, Sox2 and c‐myc, and the stemness markers CD44, CD133 and EpCAM in the normal human liver L‐02 cell line or CHL cell lines upon transfection with MCV‐HBx vectors. Stem‐like cells generated more tumour colonies compared to primary cells, and xenografts induced tumourigenesis in nude mice. Expression of reprogramming‐related proteins was significantly enhanced in HLE cells while transfected with pcDNA3.1‐afp vectors. The specific PI3K inhibitor Ly294002 inhibited the effects of pcDNA3.1‐afp vectors. AFP‐siRNA vectors were able to inhibit tumour colony formation and reprogramming‐related gene expression. Altogether, HBx stimulates AFP expression to induce natural reprogramming of liver cells, and AFP plays a critical role in promoting the initiation of HCC progenitor/stem cells. AFP may be a potential novel biotarget for combating HBV‐induced hepatocarcinogenesis. What's new? Although the relationship between hepatitis B virus (HBV)‐induced chronic liver disease and hepatocellular carcinoma (HCC) development is widely accepted, the molecular mechanism of HBV‐induced hepatocarcinogenesis remains unclear. The early HCC biomarker alpha fetoprotein (AFP) has been suggested to promote generation of HCC stem cells. Here, expression of reprogramming factors Oct4, Klf4, Sox2 and c‐myc was positively associated with AFP(+)/HBV(+) HCC tissues, with stemness markers CD44, CD133 and EpCAM expression being significantly higher in those tissues. AFP could stimulate expression of reprogramming‐related genes in normal liver cells through PI3K/AKT signalling, suggesting a pivotal role in promoting initiation of HCC stem cells.